This invention relates to the recording of electrocardiographic signal recording and, more particularly, to an improved portable recorder.
Some forms of heart disorders during their early stages produce abnormal ECG's only infrequently and sporadically. To overcome this and detect heart disorders early, portable recorders in the prior art are worn by patients which recorders continuously record the patient's electrocardiographic (ECG) signals over an extended period of time while the patient engages in normal daily activities.
Those prior art recorders comprise a battery powered magnetic tape recorder mechanism which record on the standard size magnetic tape cassettes. With speeds of only one millimeter per second, the cassette is capable of recording anywhere from 24 to 48 hours worth of data.
Although relatively small and compact (6.1" by 3.9" by 1.6" and 13/4 to 2 lbs.), the prior art devices still represent a considerable nuisance to the wearer, and any reduction in size and weight would be a welcome improvement. However, the size and weight are controlled mainly by the size and weight of the battery, motor and cassette needed to record the 24 hours to 48 hours worth of data.
Further, in the prior art devices, while the case of the recorder is still open, the recorder head and pinch roller must be moved into recording position manually. When the case is closed a start switch is manually engaged. It is desireable to have all of this start automatically when the case is closed.
Further, in many prior art recorders an oil light bearing is used with the pinch roller and ball bearings with the capstan but because of the slow recording speed the oil light bearing is often inadequately lubricated causing premature failure and the indentations in the ball bearings introduce noise in the recordings.